Busy-test system for party telephone-lines.



F. R. MQBERTY. BUSY TEST SYSTEM FOR PARTY TELEPHONE LINES.

APPLIUATION FILED DEC. 18, 1909.

Patented Nov. 26, 1912.

the multiple test terminals of current by a separate test conductor,

UNITED STATES rafrnntr OFFICE.

FRANK B. MOBEBTY, OF NEW ROCHELLE, NEW YORK, ASSIGNOR TO WESTERN ELEG- TRIO OOMPANY, OF NEW YORK, N.

Y., A CORPORATION OF ILLINOIS.

BUSY-TEST SYSTEM FOR PARTY TELEPHONE-LINES.

Specification of Letters Patent.

Patented Nov. 26, 1912.

Application filed December is, 1909. Serial No. 533,928.

Busy-Test Systems for Party Telephone Lines, of which the following is a full, clear,

concise, and exact description.

The present invention relates to a busy test system for a telephone line having a plurality of responsive devices adapted to be selectively signaled, and contemplates providing a separate test terminal for each responsive device, and means actuated upon the engagement of a switching device witha test terminal for establishing a changed electrical condition of the remaining test terminals.

It is the modern practice to impress potentialof a certain value or character upon telephone lines, the connection of the answering plug or other connecting device with a test terminal causing a change in the electrical condition of its multiple test terminals, this changed condition serving as a warning that the line has been taken for use.

In accordance with this invention when each of two stations of a party telephone line is equipped at the central oflice with line terminals and a test terminal, and each test terminal is connected with a source of a magnet provided in each test conductor adapted to be energized upon the engagement of a connecting device with a test terminal, to cause a change in the electrical condition of the test terminal of the other substation.

In the present embodiment of, the invention in a four party telephone line, a test terminal is provided for each substation of the line, and a test conductor may connect the test terminals of thesubstations having responsive devices in different ground branches from opposite sides of the line and adapted to respond to current of a certain c-liaracter with a source of current, and a second test conductor may connect the test ter'ininals of the other two substations having responsive devices-also in different ground branches from opposite sides of the line and adi'ip't'ed to respond to current of another character with a source of current diilere'rit I drawing, which first test conductor. A responsive device, which may be a relay, is included in the circuit of each test conductor and, upon the engagement of the connecting. device with a test terminal, may change thepotential applied to its associate test terminal, and close a local circuitincludmg the other test conductor, thereby changing the potential applied to its associate test terminals. A busy test potential will thus becaused to exist upon the test terminal associated with each substation. "In the present embodiment of the invention, thebusy test condition of the test terminals is indicated by a reduced potential. This result may be accomplished by providing a pair of relays, one in each test conductor, each adapted to reciprocally control a local circuit including the other, the arrangement being such that one relay will be rendered active, upon the connection of the switching device with a test terminal to close a local circuit through 'ithe other differentially. This may be brought about by having the local circuit of each relay open at an armature contact of the other.

The system of circuits herein described embodies certain features of invention which are not claimed in this application. These are made the subject-matter of my copending application, Serial No. 573,517, filed July 23, 1910.

The invention will be particularly described by reference to the accompanying illustrates its application to a semi-automatic telephone exchange system, certain circuits and apparatus necessary to a complete disclosure of the invention being also shown, it being of course understood that the invention is in nowise limited to such a system, but is just as well adapted for use with either full automatic or manual telephone exchange systems.

brushes of a final switch or connector, which is adapted to be rotated about its axis X X to advance the said brushes to the terminals of apredetermined line by automatic mechanism under the control of an operator. The contacts 16, 16 control the completion of the circuit from the calling party to the called party, and may be operated manually at the time the brushes make connection with "the desired terminals. provided the line is flee, but are preferably arranged to be In the drawings, 19, 20, 21 represent the closed by an automatic switch under the controlof the calling operator when con nection is made witha tree line, and may be prevented from operating when connection is made with a busy line. The contact 14 may be adapted to be closed by the mechanism which controls the closure of contacts 16, 16 or may be manually operated. In the former case this contact is closed immediately upon the engagement of the brushes with the desired terminals, but should such line be busy, ringing current will not be impressed upon it, because the contact 16 will not be closed.

The line conductors l, 2 are multiplied, as shown, one set for each substation of the party line, the terminals 1 2* being the terminals of substation A, 1, 2*, for substation B, 1, 2 for substation C and 1 2 for substation D. These multiple terminals may not necessarily be adjacent each other upon the terminal support of the, connector, but may be distributed, as shown among terminals which may lead to single lines, trunks, etc, and may even be located upon dilierert connectors according as'traflic conditions may require. The line conductors 1,

2 are extended as shown and may lead tomultiple terminals of the party line upon other connectors or may terminate in springjacks in a manual exchange.

The signaling and telephonic appliances represented at the substations are of wellknown'type and therefore need not be particularly described, it being sufficient to merely say that two of the bells, those at stations A and C are oppositelypolarized and placed in independent ground branches from line conductor 2, and that the other two bells, those at substations B and D are also oppositely polarized and placed in indepelndent ground branches of line conductor In order that the invention may be more readily understood, means are shown and will be briefly described for automatically selecting and impressing upon the line the particular character of current required to operate the responsive device of the predetermined substation upon the engagement of the connector brushes with its terminals, provided the desired party line is not already in use at another multiple terminal of the party line, in' which case the contacts 16, 16* will remain open, thus preventing ringing current from being. impressed upon the line. 7

The line conductors 1, 2 are mu'ltipled to the tip and ring of the jack of an answering operators connecting circuit, which jack is adapted to be engaged by the associate d plug. When a subscriber on the party line removes his telephone, therebyenergizing the line relay 6, a circuit is closed from grounded battery 7 through the usual line lamp 8 to ground at '22, signifying that a connection is desired.

A test terminal is associated with each 'set of line terminals on the connector and also with the answering jack. The test terminals 3 and 3 of stations A and B ada ted to be signaled by current of the same c arductor 3, the test contact 3 of the jack being also connected with said conductor for a purpose to be later set forth. The test contacts 3 and 3 of substation C and D adapted to be signaled by current of the same character, though different from that applied to signal A and B, are also connected together by a test conductor 4. Current of negative polarity may be impressed upon test conductor 3'and consequently its asso: ciate test terminals. Current of positive polarity may be impressed upon test condoctor 4 and its associate test terminals.

For convenience in describing the manner in which the potential of the sources of current of different characters impressed upon the test terminals may bereduced, .a. battery 35 is shown having its free pole, which in this case is negative, connected ,with test conductor 3 and its positive pole grounded. It has been found in practice that the potential of this battery maybe 48 volts. From the middle point of this battery a conductor 25 is connected to the test brush 21. The

'acter are connected together by a test contest conductor 4 is connected to ground V at 22. v A

It will thus be evident that the test terminals 3 3 and 3 have a potential of 24: volts minus with respect to test brush 21 and conductor 25, and that testtermin'als 3, 3, being connected through relay 5 to ground, have impressed upon them a potential of 2st volts plus with respect to test brush 21 and conductor 25. v

With this explanatiom'it will be. clearly seen that the test terminals 3, 3, 3 may be considered as being impressed with negative potential of 24 volts and that; the "test terminals 3, 3 may be consideredas being impressed with positive potential of 24 volts.

A cut-ofi relay 5 is included in test conductor 3 and a cut-off relay 5" is included. in test conductor 4. Both of these relays are adapted to be include d"in the circuit of their respective testconductors upon the engagement of a test brush ,with atest terminal. A convenient "t' arrangement for accomplishing'this I, lsgmade by providing each cut ofi rel addition to the usual energizing winding ferential windingj iZLtappcd onto the energizing winding and havinggits circuit normally open at the armature collect of the oppositerelay, so that uponthe-j actuation of either cut-off rfliy 5 or 5" by a flow of current through the corresponding test conductor 3 &4, dueito the connection of the test brush with a test terminal, a localcircuit 12'or 13' is closed including the opposite relaydifi'erentially. It has been found in practice that the energizing windings of each of 'the cut-ofi' rela s 5, maybe of 100 ohms resistance an that the resistance Y ot'the differential winding may be 50 ohms.

. of'theconnector to the middle of the battery or ground, and a 'circuitis adapted to be closed through-this conductor upon the connection of "said-brush. with a test tenni 'nal, provided-the line is free, which will be Q indicated by the presence of normal potenspond to positive current from test brush --tial thereupon. A'relay 1I,polarized to re- 21 only, is included in abranchof conductor 23,'and is adapted normally to connect a source of negative ringing current 15 with a conductor 18 leadin to the ringing brush 20 upon the connection of the brushes with the terminals of a substation having a'test terminal fupon which negative current is impressed, substation'A-or B, but upon the connection of the brushes with, the terminals of a'station having a test terminal upon which positive-current is impressed, substation B or C, the relay will operate to shift the ringing lead to a source of positive current 15". In order that the same brush may serve to conduct the ringing current over both sides of the line, the "connections of the leads from theconductors 1, .2 to the line terminals. of two substations are re 'ersed with respect to those of the remaining two substations. jIt'wilL'Qt' course, be understood that the sources of current 15 and 15! may be of any character suitable for the purpose of signaling and'that there is no significance in the coincidence that in this particular case-the negative potential selects negative current and the positive potential positive current. a

' 'lherehergization of-the cut-olf relays 5 and- 5 is controlled by the relay 10. This relay has two windings of different resistanres. The high resistance winding is included inseries with the relay 17 upon elosuroxofthe contact 14 and the low resistam'o'winding isdncluded in a shunt about the relay 17 which is closed upon theenergization of the relay 24. If a multiple terminal of the party line is in use a reduced potential will cizist on the test terminals of the "selected line. \Vhen the test brush ma kesconnwtion to a test terminal on which reduced potential exists, the relay 10 will not be energized on account of the low potential 1:11 the test terminal. However,

should no substation of the party line be in circuit through a relay 24, which inturn" operates and shuntsv the high resistance winding of relay '10 to provide a margin of current for the 'energization of the cutoff relay associated with the test terminal of thellne taken for use, which in operating closes a local circuit through the neutraliz- Ting winding of its companion relay includin the other test conductor, ,thus causing a re notion of potential upon the test terminals of the party line and upon their .multiple test terminals, to prevent I'the operation of a corresponding governing relay at a connector upon which a multiple'terminal" of the party line is located.

Assuming connection is desired with substation- A and the party line to be free,- the cpnnector' switch is advanced until its brushes 19, 20, 21 are in contact with terminals '1, 2, 3 of the desired substation. Current of a negative character is now impressedupon the line andringsthe bell of substation A over the following. circuit: from generator 15, conductor 18, contact 16, (which is closed at this time) conductor 11, the middle brush 20 of the connector switch, line terminal 2, conductor 2, and to ground through the negatively-polarized bell in the grounded branch at station A. The connection of the brush 21 to the test contact 3 closes a circuit for the relay 10 which.,subsequently causes the energization of relay This'circuit may be traced as follows: from the free pole of battery 35, conductor 3, in which is included the relay 5, test contact 3, brush 21, conductor 23; relay 17. high resistance winding of relay 10. conductor 25 to the neutral point of said battery. The relaylO is a quick acting relay and immediately draws up its armature, closings cire cuitfrom its grounded armature. contact 31,

conductor 32, in'which is included relay 2%,

to the free pole of battery The armature ofrelay 24 is now attractedand closes at its contact a shunt of thehigh resistance winding of relay 10 through the low resistance winding, the circuit for which is closed at the armature contact of relay 24. The relay 5 is marginal in operation. and will be energized immediately upon the operation of relay 24 and the consequent reduction in the resistance of the circuiFdue to the shunting of the high resistance winding of relay 10. The cut-oil relay 5 upon its excitation attracts its til-matures, thereby opening the circuit of the line on one side at a contact of spring 29 anC n the other at contact leading to the lin relay 6. The

mil: ee... e e -119 i 1 a kasoppeslte to'that.

1 firentifl'owninlocah'cii'euit 12 is derived frornf;the sourceg-epplyinglgpotehtialaof;a-

unpoeit ive chgiectteff u n-test terminals? 4" cut oif, relays Q fen w ex ti llcondo'toisg 6" {battery B 111abeinotecl i that since the res'ist'enceo glifi'erential windings'of the equel; to: that of the. low,

' "resistancegwindin ofreley {10, the potential r impressedlupon at estest, terminals of -con5=,

.d iie'tor i will berr'ed libed in Iike'menh'erith that impre$ed 11pon the I test{ te1"m ma;ls of conductor; 3, -.therebyprovidin i-forthe pye-g. ,ventionxof a bus :li'ne bemg-ta en-foj17 u se'at;

. 1 a multiple: teringnal. of thefperty .fline; q 2e, 2 5' i I with heternlinals ihstationC Un -D; for inste'nee- G positive "current only, and assuming noother is operjitedientli attracts its axzmatupgf clo sing at ltstloivelfleonlnot"a cil cultlforgl mginggf currenti o f ipc sltlveslgn from enerator 15;

l to operate 1 the .positivelyil'biase bell in -ithe'. t-oitnfl branch at substatlonvG,througheon--- w 5 tron w1t-h hne .term1nals' for each of two uctor 1s,;c nm-1c, '(closedgsatg' thisitilh) conductor:11; brush'.v20,- terminal 32", condudton-Q to ground at Q zcausing the bell to the suhscr ibei' ofl'a call. In

. and 10, 1 This circuit m'zpybe traced 51s follows .*relay 5f,lcof1ductot;4,1;test terminel' 3% test .fiom' "groun dizat- 22, lenergizingwinding of a sistqnce minding off-relay; 10,--vconductor 25] th'e test.-.pbtentiall impresscc upon test till-- in as: essential that, a: busyondition. be

battely Y 35,-cpnductor- 3 through relay difierentially;#concluctor. 3,4; armature v35,

ihaintainediufion the test terminals of theparty line when a, cell f rom-any ofi them is of the party line is-nowfredu I4 b xe n air'l po'nith rep fi :t-he recei veg'hythe subscriber}'-the eit c ti of. relay 39, {which nelay} by its enetgizationin a'f circuit closed throughithe sfihstationftelephonic app'ap'at-u's i maintained 'pen the 1 ciru h i n' 'ws-t. th ll n b t 'th {bifing tel-contact? leeing en'swered and while connection is bemg extended and until connection has been ta,ken"'dpwn.- In'ordento accomplish' this result the? test, thilgibl'e 101 sleeve 3 of the from this party;- I

conduetofi- 3, as Before the free pole of battery 85,-. ;Th -i' ohms. 3 The cutgofi -*'re'laiy; 5; in operating closes at-jv contact ,9' -the 1ocal1'circuit 12 Binpotential npon thei-jmultipl t cult of supervisolyiliimp 1 3B; -i now deneh causes superviso'iy' amp, 3 8 to beilhimh'iated relay 10- to the? freefpoleg ofia:battei y 40;

normal. 1

, Having hug-described *ieyei vhlibn I f, Ineparty teleiihone lihe, the cornhlnw stations, of a test tefmineil for each station, a test; conductor connecting each vtest; tenhitors, endij'a' responsive device v in .eachtest' 'the' of relay'lfifnmybe the seyneiafsfthe-lowleslstance jvlndingi ofi'i'elay'" '10,: "namely" 50 -na,l with a source of "cnrrenh a switch adapt- 4 ,ed. to lengage ivithl-seid terminals endelos'e condizctozi;.aiiapted .-to close 'a iclgcuit jineluding the other test condlictor.-'-

" I pa ty ficelepho'n'e line, th'coxnhinh -.-t-ion with T line.ktegmina ls', fogeach OfgtWO :stajti ong; terhlinal rf o chistpt lon, test conductors connecting'sa ,est-tefinihals' said switchin'gifdefie inkl sing saidcircult saldmeans thnz'zi'ctlieitiijlgmeans for-caust l'appli ed to the nilnaL- joining. said test terminals, with stations,- a" test terminal "for each station,

mtwo test conductors,"onetor eachtestter minal, joining said terminals withisource's a" switchl of 'current of opposite .polarity test -termi'nal s and thereby a icircuit therethrough, -and j a responsiveldevicei in' eachtest;con'cluctor' adapted -t'ofclose ai localf circuit" includingf tlii other T test 0 duster. 5,*i[n:a: artjg le hoire-iiiie, mung: v tionwith in?terminals-for'ieach oft sta, 2o tions, a testfzterminal for Teach ta'tionfgtest conductors iconnecting said itest g p withsou'resfof current 6-opp6ite p1arity, a switching device adapted to engage with. said terminals and complete 'alcircuit includ; ing one "of said test-terminals, in eans .;or

chalging '(thefpotentialfoffsaid circnit 'ar-j ranged" to'ibe 1 introduced by t-he said. switch 4 ing deviceiniclosing said circuit a ass;- actuated'inturn-=by said other nsan -"01.- causing .a phangein otential' cbetween'jthe othertest terminal an stump traumas- 6. In a party telephone the "coinbina-f tion with line. terminals for "afidftfiti stations, aytest'g terminalgfor f "eachTstation, j test conductqrs" icdnnectingfsaid "test ter minals with sources' of warmed .j'difierent" gage With said' terminals" and complete a circuit includin one; of said terminals, 40 means forpro ucing' current ,rchangesfar-. ranged to be introduced'bythe-saidswitchg'ing'fdevice in closing said circuit and means, actuated -.in ,turn gby lsaid other 1 means, for causing a change in the character of the l 46 current applied to the other test terminal. 7. In a party telephone line," the combina tipnwith line {terminals for each of two Q stations, 11' test terminal for'each station, it test wires connecting said test terminals 2 '50 with sources? of current, a switching device adapted to engage said terminals .x'and -thereby fto close-acircuit including one of said'test tenninalsfor reducing the potential I applied'to'said test terminal, and a cut+ofi1 56 relay included in said circuit, sa d relay i 'in' operating being adapted-to closea cir- 'cuit having inclu ed therein means-tor 'rev .ducingtthefotential applied to the-other a termin a 60' 8. In a party tele hone line, the combinetion with .a meta 1c telephone 'line, of a pair of res nsive d vices in -diiierent groundvbranc es from e ch line conductor,

' the' qnsivedevices in branches of the same line conductor being adapted to re tion with line terminals for each oftwo adapted as make connection anthems ase m nals...-

v a ductor'adaptedto' b selectlyely slgn l d conductors each connecting testfterrninal assoc atedv w1th each sidefof the line'with'gof v devices 1- in 'different lay including the .other relay.

spond to current of difierent character, a set of terminals for each station consisting of two line contacts and a test contact, two test'conductors each connecting test terminals "associated with each side of the line with sources'of current of opposite polarity,

-aswitchin g deyice' adapted to engage with said terminals and thereby to complete a circuit including one ofsaid sources of current and "its associate test. terminals, acut ofi'relay includedlinsaid circuit, and alocal circuit including a resistance, said cut-ofi' relay: upon itsfenergizationclosingsaidj local I". 'circuit a'nd including the source of:currenti {of the other: test terminals 'through said rego sistanc'e, i whereby "the potential otj t-li eftes't A- :j iterminals 'ofboth'sides off-the line i -31 nationf -wit p I v v having apair of responsive deyicesiin dif T radi d party:telephone-ling f a pa r of-- met'allic""co u'ctors ferentfground; branches from each line to of a' test terminal for=each station; two fjte'st local circuits each with a connect on Y to 'one [of said'gcut 'ofi relays, and a switching -.de viceadapted ,to close the circuitof-oneof said sources of current through onejof said I;

r lays; and therebyfto comdetea'local cir-f 'f' .jcuit'- includin""th'e" other re ay, upon its en'- I igagelnent wit any of'said test terminals. 'Q '1 10.? In fa semi-automatic party telephone 10o line, the "combinationwith a pair of me w character, a switching devie adapted to en tallic conductors having a pair of responsive v 'ound branchesirom' each lineconductor a apted to'be selectively signaled','-of atest terminal for each station, 105 two test "conductorseach" connecting 'test *1 I terminalssassociated with each sideof the I -l1ne with sources of current of opposite-po "larity, two cut-ofl relays, two local circuits each-with-a connection to one of said cutofi relays, and a test brush adapted to close the circuit-of one of said sources of current thr'oughone of said relays and thereby complete a local circuit including the other reay upon its engagement. with any of said test terminals. vv 1 v 11.; In a semi-automatic party telephone line, the combination with line terminals" and aftestterminal "for each of two stations,

testico'nductors connecting said 'test terminals with sources of current of opposite polarit a cut-off relay in-each test conductor,

two ocal circuits each with a connection to,

one ofsaid relays, and a test brush adapted to engage with said test terminals and thereby to complete the circuit of a test conductor includmg one ofsaid sources of current and the corresponding relay, and a local circuit controlled by said-last mentioned re- 

